Valve lifter cylinder and method of making same



Aug. 5, 1958 A. H. COBQ VALVE LIFTER CLYINDER AND METHOD OF MAKING SAMEFiled July 20, 1955 INVENTOR. 0

ATTOPNEY United States Patent VALVE LIFTER CYLINDER AND METHOD OF MAKINGSAME Alfred H. Cobo, Grand Rapids, Mich, assignor to General MotorsCorporation, Detroit, Mlch., a corporation of Delaware Application July20, 1955, Serial No. 523,288

4 Claims. (Cl. 123-90) This invention relates to valve lifters foroperating poppet valves and the like in response to movement imparted byan engine driven cam, and particularly to cylinders for such lifters ofthe so-called hydraulic type.

A design of such lifter which is in most common use today comprises acup-shaped cylinder arranged upright on the cam of the engine andslidably fitted with a plunger which rests on a body of oil in thebottom of the cylinder and transmits lifting movements of the cam to thepoppet valve or its operating push rod. A spring interposed between thecylinder and plunger acts to take up lash in the valve train followingeach lift stroke, with the result that the volume of the oil body belowthe plunger is increased, and additional oil for this purpose is allowedto pass into the lower end of the cylinder through a one-way passage inthe plunger. This additional or make-up oil is contained in a reservoireither within or above the plunger. The bore of the cylinder has a closesliding fit with the plunger to permit a controlled leakage of oil fromthe lower end of the cylinder during each cam lift stroke, therebyproviding a slight foreshortening of the lifter during each lift stroketo ensure its over-all length will not prevent full return movement ofthe valve or other device actuated by the lifter.

Experience in the operation of such lifters, especially those in whichthe reservoir is supplied from the engine lubricating system, has shownthat varnish-like material and other foreign particles from the oiltends to deposit more readily on those slidably fitted surfaces of theplunger and cylinder bore which are not covered by the other. To preventsuch deposits from becoming jammed or wedged between those surfaces andinterfering with the necessary foreshortening of the lifter it has beenthe practice to relieve those portions of the cylinder bore and theguided surface of the plunger which would otherwise slidably engage theother as the plunger moves inwardly of the cylinder. Such relief of thecylinder bore is required adjacent its inner or closed end and hasheretofore been accomplished by either undercutting that end of thecylinder bore with a suitable boring tool inserted through the open endof the cup, or by counterboring that end of the tube before attachmentof the cam engaging foot. Such machining operations have increased thecost of such lifter cylinders, not only because of the time and toolexpense involved, but as a result of wastage of metal which this methodnecessitates.

It is a principal object of this invention to reduce the cost of such alifter cylinder by forming it of a plurality of concentric tubes and afoot portion, with the inner of the tubes terminating spacedly from thefoot and the corresponding end of the outer tube being joined to thefoot to thereby form such bore enlargement.

The formation of the side walls in this manner from a plurality of tubeshas a further advantage in making such cylinders which are also to beprovided with an external annular groove adapted to communicate withgether by the inner tube which forms the bore for the lifter plunger.

H The means for carrying out these and other objects of the inventionwill be more readily apparent from the following description, havingreference to the drawing' wherein:

Figure 1 is a longitudinal sectional view through a hydraulic valvelifter having its cylinder constructed in accordance with the invention.

Figure 2 is a transverse sectional view taken substantially on line 2-2of Figure 1.

Figure 3 is a view similar to Figure 1 showing the same lifter modifiedto provide the external annular groove about the cylinder betweenadjacent ends of two axially spaced outer tubes.

Figure 4 is a transverse sectional view taken substantially on the line44 of Figure 3.

The lifter shown in Figures 1 and 2 comprises a cupshaped cylinderindicated generally by the numeral 1 in which a plunger 2-is slidablyreciprocable and is adapted to rest on a body of oil contained in apressure chamber 3 between the closed end Wall 4 of the cylinder and theplunger. A plunger return spring 5 is shown within this chamber 3 forbiasing the plunger outwardly of the cylinder to take up lash betweenthe engine cam (not shown) on which the cylinder rides and the enginevalve or pushrod (not shown) which thrustably abuts the upper end of theplunger.

The plunger 2, in the particular design shown, comprises, a cylindricaltubular member 6 plugged at its opposite ends by a check valve seatmember 7 and a push rod seat member 8. The interior of the plunger formsa reservoir 9 which supplies the pressure chamber 3 through a checkvalve controlled passage 10. The check valve controlling this passage isshown as a ball 11 retained within a cage 12 held in place against theseat member 7 by the plunger spring 5. A lighter coil spring 13 biasesthe ball to its seated position closing the passage 10. The upper orpush rod seat member 8 is also shown as having a passage 14 throughwhich excess oil supplied to the reservoir h may be metered under thecontrol of a flutter valve 15 loosely retained in the lower end of themember 8 by a ring 16.

The plunger 2 is shown in its approximate mean operating positionlongitudinally of the cylinder 1, with the slidably guided outer surface17 of the plunger extending well into the pressure chamber 3. In otherwords, the upper portion of the chmaber 3 surrounds the lower portion ofthe plunger guided surface 17 to a sufiicient height above the plungerlower end that even with the plunger positioned at the extreme upper endof its operative travel the bore 18 of the cylinder 1 is never exposedto the oil in the pressure chamber 3. Any suitable means, such as anoutspringing snap ring 19 engaging a groove in the upper end of the bore18, is provided for retaining the plunger and cylinder in assembly whenthe lifter is removed from the engine.

In accordance with the invention, the cylinder 1 has its side wallsformed of concentric inner and outer tubes 20 and 21, with the lower endof the outer tube being permanently and sealingly joined to theimperforate cam engaging disk or end wall 4 as by brazing indicated at22. As shown, this end wall piece is provided with an annular portion 23extending into the outer tube to form a socket laterally locating theplunger return spring 5, and an abutment surface 24 which serves as astop to limit extreme movement of the plunger inwardly of the cylinder.The inner tube 20 lines the outer tube 21 and treminates at its lowerend 25 in spaced relation from the foot piece 4 to provide the sameefiect as obtained in the prior art by the aforementioned enlargement ofthe bore 18. The two tubes 20 and 21 are fixed to each other and sealedagainst escape of oil from the pressure chamber 3, as by coating theirinterfitting surfaces with cooper or other suitable brazing materialbefore assembly and then heating to effect a solid bond between them.

The particular lifter shown is of the side fed type, i. e., thereservoir 9 is supplied with engine lubricating oil conducted to thebore (not shown) of the engine in which the cylinder is reciprocallyguided. For this purpose, the outer periphery of the outer cylinder 21is provided with an external annular groove 26 adapted to maintainregistry with a port in the cylinder guided bore, and connecting thisgroove with the interior of the plunger are aligned ports 27 and 28 inthe respective tubes, overlapping internal and external grooves 29 and30 formed in the bore 18 and the plunger external surface 17, and a port31 in the plunger wall.

In the modified construction shown in Figures 3 and 4, the single outertube 21 is replaced by two axially spaced tubes 121 and 221, with thelatter tube being connected to the cam engaging foot piece 4 at itslower end, and the axial space between the tubes 121 and 221 definingthe upper and lower extremities of the groove 126. The inner tube 20 isidentical with that of Figures 1 and 2, and may be fixedly and sealinglybonded to the two outer tubes by copper brazing in the same manner, orby employing a sufliciently tight press fit between their respectiveinterfitting surfaces and tack welding at various spaced points asindicated at 140. As will be appreciated, this form of my invention hasthe additional advantage over that shown in Figures 1 and 2 ofeliminating the step of machining the cylinder external groove, whileretaining the advantages of eliminating the necessity of machining toprovide the necessary relief for the lower end of the cylinder bore 18.

I claim:

'1. In a hydraulic valve lifter cylinder member having a tubular portionand a cam engageable foot fixedly and sealingly connected to one endthereof, said tubular portion comprising concentric inner and outertubes of difierent lengths secured together with the foot adjacent endof said inner tube being spaced endwise of said foot to form a radialenlargement of the bore of said tubular portion, said outer tube havingan external groove intermediate the ends of said inner tube, said innertube having a port communicating with said groove and open to the boreata distance from said enlargement.

2. In a hydraulic valve lifter of the type having a cup- 4 shapedcylinder with a plunger axially reciprocable therein and defining achamber for thrust transmitting fluid between the plunger and the endwall of the cylinder, said cylinder having its side walls constituted bya plurality of tubes including an outer tube defining the lateralextremities of said chamber and an inner tube lining said outer tubeoutwardly of said chamber, said plunger slidably fitting the bore ofsaid inner tube and extending into said chamber throughout the operativerange of movement of the plunger.

3. In a hydraulic valve lifter having a generally cupshaped cylinder, aplunger reciprocable therein and a body of fluid thrustably supportingthe plunger from the end wall of said cylinder, said cylinder having itsside walls constructed of a plurality of concentric tubes including anouter tube terminating sealingly and fixedly at one end with thecylinder end wall, and an inner tube lining said outer tube and spacedaxially thereof from said end wall, said tubes being fixed and sealinglybonded to each other against escape of fluid therebetween from saidbody, said'plunger having a cylindrical external surface slidablyfitting the bore of said inner tube adjacent said body and extendinginto said body beyond said bore throughout the normal operative range ofplunger movement.

4. In a hydraulic valve lifter having generally cupshaped cylinder andplunger members in slidably nested relation defining a fluid pressurechamber between their respective end walls and a fluid reservoirinteriorly of the plunger member, said cylinder member having its sidewalls constructed of a plurality of tubes of difierent lengths includingtwo aligned outer tubes axially spaced from each other to define areceiving groove therebetween for fluid to be supplied to said reservoirfrom a source externally of the lifter, and an inner tube sealingly andfixedly interconnecting said outer tubes, said inner tube having a sideport connecting its bore with said groove for the passage of saidexternallysupplied fluid, one of said outer tubes extending beyond thepressure chamber end of said inner tube and terminating fixedly andsealingly with the end wall of the cylinder member, said end of theinner tube being overlapped by the plunger member throughout the normaloperative range of relative movement of the plunger and cylindermembers.

References Cited in the file of this patent UNITED STATES PATENTS2,178,732 Voorhies Nov. 7, 1939 2,652,038 Winkler Sept. 5, 19532,680,901 Kaiser June 15, 1954 2,689,554 Moser Sept. 21, 1954

